This invention relates to tube-type vortex ring mixing and/or agitating apparatus and methods for use with fluids. The apparatus and methods can also be used for the efficient addition of solids or liquids to a fluid during a mixing and/or agitation process.
The concept of vortex rings in fluids has been known for many decades. Vortex rings can occur naturally and can be created in various ways such as mechanically by the impulsive ejection of a slug of fluid from an orifice. Some examples of vortex rings are gas or smoke rings, and the smoke and/or gas rising from an explosion, such as an atomic explosion. A vortex ring can be generated by many simple devices e.g. from a tube or an orifice, by impulsively blowing into one end of a straw immersed in a liquid or when an immersed jet is started. Although a vortex ring can be produced relatively easily, there are particular criteria which absolutely must be followed if energetic vortex rings which will travel relatively long distances before their self destruction are to be generated efficiently. The design and operating criteria of the equipment to produce and propagate vortex rings is therefore very important, if the rings are to be produced efficiently for mixing or agitation purposes.
There appear to be no suggestions of the use of ring vortices for the specific application of the mixing or agitation of fluids in enclosed boundaries, such as mixing vessels and tanks, with the exception of copending U. S. Pat. application No. 369,802 filed June 22, 1989 by the present inventor.
U.S. Pat. No. 4,452,634 (Oguchi et al) does describe some very simple equipment which uses pulsed flow from a tube immersed in liquid steel for mixing the steel, but there is no reference to vortex ring generation. The obvious difficulty when pulsing the liquid in a large diameter tube with direct gas/liquid interface and gas as the transfer media, is that large volumes of gas are required to drive the unit resulting in slow pulsing and considerable waste of energy during the compression and expansion process. It also results in poorly sustained immersed liquid jets which produce local mixing in the vicinity of the orifice or jet, but are quite poor mixing processes for the entire volume of liquid to be mixed.